Most people think that if they were having a heart attack that everything would stop and they would absolutely know that they are having one but new studies show that this is not necessarily the case. Although in most situations, you will recognize a heart attack, new evidence suggests that people have silent heart attacks as well at an alarming rate.

They discovered 8 percent of the participants showed evidence of scarring-damaged tissue-on their hearts.

Of that scarring, the majority went unrecognized and uncared for, and nearly half of those looked typical of a heart attack.

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That means they may have experienced a heart attack and not even known it.

“In some cases, patients have symptoms that they feel are not bad enough to go to a doctor,” says study author David Bluemke, M.D., Ph.D., the director of radiology and imaging sciences at the NIH Clinical Center.

Those symptoms may include mild chest pain, nausea, vomiting, unexplained fatigue, heartburn, shortness of breath, or discomfort in the neck or jaw, he says.

That’s right: A silent heart attack may feel a lot like a bout of the stomach bug or the flu or indigestion. Unlike those illnesses and ailments, however, even a mild heart attack can leave scar tissue on your heart.

For younger, healthier guys, the chances of this being a heart attack is very rare, says Dr. Bluemke.

But if you’re over 50, 40+ with a strong family history of heart disease, or have other risk factors like obesity, high blood pressure, diabetes, or smoking, you should head to your doctor as soon as possible if your symptoms persist longer than 20 minutes or seem to worsen with activity.

Even if you’re not having symptoms, it’s a good idea to see a doctor for an annual physical, too.

That’s because an unrecognized heart attack isn’t the only thing that can scar the organ: Things like chronic high blood pressure, diabetes, obesity, and smoking can also damage the heart.

In fact, 70 percent of people with unrecognized heart disease who died of sudden cardiac death actually showed previous scarring on their hearts, a previous study found.

That’s why early detection of heart disease is important, so your doc can control those factors before a heart attack hits. You should also ask your doctor for a CT calcium score or CT angiogram test, says Dr. Bluemke. These can detect plaque buildup at a very early stage.